Electric-wire insulator



(No Model.)

J. F. MARTIN.

ELECTRIC WIRE INSULATOR.

No. 287,146. I Patented O0t.2 3, 1883.

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UNITED STATES PATENT OFFICE.

JOHN F. MARTIN, OF CHICAGO, ILLINOIS.

ELECTRIC-WIRE INSULATOR.

SPECIFICATION forming part of Letters Patent No. 287,146, dated October 23, 1883.

Application filed January 27, 1883. Renewed September 2, $83. (No model.)

To (LZZ 107mm it may concern Be it known that I, J OHN F. llIARTIN, a citizen of the United States, residing in Chicago, county of Cook, and State of Illinois, have in vented certain new and useful Improvements in Electricire Insulators, of which the following is a specification.

My invention relates to improvements in wire insulators having a tubular form, and adapted to insulate wires arranged in underground conduits, houses, Ste. but more particularly designed to perfect an underground electric-wire system for cities and towns, forming the subject-matter of another-application.

lhe objects of my invention are to provide means for riveting individual wire-insulators of tubular form, and composed of sheet-paper or woven fal)ric,by means of a compound which, while performing the functions of a rivet, will have an auxiliary effect in insulating an electric wire confined by the insulator; to provide means for riveting a tubular insulator of the character and in the manner described, and at the same time incorporate therewith a layer of rubber fabric or compound or otherinsulating 1naterial,which in the completed tube shall lie intermediate and be confined and protected between the inner and outer walls of the insulater. I attain these objects by devices illustrated in the accompanying drawings, in which Figure 1 is a perspective, in a partially-finished state, of an insulator embodying my invention; Fig. 2, a plan view of the same,with the perforations, on an enlarged scale; Fig. 8, a cross-section of Fig. 2; and Fig. 4, a plan view of a blank for insulators embodying my invention, and when provided with an intermediate layer of rubber or other non-conducting fabric or compound.

Similar letters of rcferenceindicate the same parts in the several figures of the drawings.

A represents an insulator for individual electric wires, and composed of sheet-paper or woven fabric wound in concentriclayers about itself in tubular form, the inner diameter of the insulator being sufiicient to permit the ready insertion of the wire at any time after the insulator is completed. As shown in Fi 1, the paper is perforated before rolling, as shown at u,said perforations being arranged without any design as regards their order, but

has fully and solidly filled them.

preferably should be substantially evenly dis tributed over the sheet. After perforating, and before rolling the sheet into the form of an insulator,the sheet is coated, so as to fill the perforations with a non-conducting and adhesive compound,which may be of pitch, resin, or of any substance or substances having the abovenamed characteristics, said compound being applied in the heated state and the insulator formed before the compound cools. By this process the compound is firmly compressed in the perforations, and when cooled causes per fect adhesion of the layers of paper or fabric, and as a result the walls of the insulator are solidified, and, as it were, riveted together,wl1ile at the same time a substantial part of the insulator is composed of a compound evenly distributed without materially increasing the thickness of its walls.

In Figs. 2 and 3 the perforations are shown arranged in regular series, and in such amannor that they are coincident with each other, and extend entirely through the walls of the insulator when in its completed form, which perforations may be made before or after the insulator is formed. These coincident perforations are filled with the non-conductive and adhesive compound by dipping the insulator one or more times in or until the compound Another method is to dip the insulator while on the mandrel in the compound and hold it there until the perforations are filled, the mandrel operating as a bottom to the perforations and retaining the compound until it has solidified in the perforations, and at the same time preventing the compound from smearing and rendering irregular the inner walls of the insulator. The same result may be obtained by omitting to perforate the first and inner layer or coil of the paper or fabric.

Perforations coincident with each. other that is, a perforation extending continuously through or nearly through the walls of the iir sulator-provide forsolid masses of a non-conducting compound riveting the several coils together, and not only render the insulator much more substantial and rigid, but a more effective insulator.

Among the advantages arising throughfornr ing an insulator ofpaper or woven fabric coiled about itself is that of providing a ready means for inserting and effectively protecting asheettected upon both its inner and outer facesby rubber fabric or compound, forming a tubular the paper or fabric. 2o insulator intermediate the inner and outer Having thus described my invention, what I walls of the insulator. This may be readily claim, and desire to secure by Letters Patent, 5 understood by referring to Fig. 4, in which E is represents a sheet of rubber laid lengthwise 1. An electric-wire insulator the walls of upon the blank of paper or fabric about to be which are provided with a series of perfora- 25 rolled in tubular form for an insulator. This tions filled with a non-conducting compound, rubber sheet should be of sufficient width so substantially as described.

10 that when the blank is rolled in the direction 2. An electric-wire insulator composed of indicated by the arrow to completely encircle sheet-paper or woven fabric wound in concenand form a tube surrounding so much of the trio layers about itself in tubular form, and 30 paper or fabric as is between the rubber and having incorporated therewith the rubber the axis of the insulator. The position of the sheet or compound, substantially as described.

I 5 rubber relative to the inner and outer walls of JOHN .F. MARTIN.

the insulator is determined by its relative po- Witnesses: sition to the ends of the blank; but in any case W. W. ELLIOTT, the rubber should be placed so as to be pro- J NO. G. ELLIOTT. 

